Across the globe, the welfare of sport horses is of growing concern, prompting the International Equestrian Federation to state that at all times the welfare of the horse must be paramount. Expressions of discomfort or pain are nevertheless frequently overlooked or misunderstood, and warrant the development of objective welfare assessment methods for the ridden horse which can be applied during training and competitions. The recent "Ridden Horse pain Ethogram" (RHpE) (Dyson et al., 2018, J. Vet. Behav. 23, 47-57) seeks to identify pain in horses based on their behavior while ridden. The ethogram includes 24 behaviors and it has been proposed that the presence of 8 or more of the 24 behaviors is likely to reflect musculoskeletal pain. Behavior-based pain scales hold promise as a means to improve the welfare of the ridden horse. That said, it is important to recognize that, as a pain or lameness diagnostic tool, the RHpE is still in its infancy because, as we point out in this review, there are a number of aspects that require further qualification before it can be applied with confidence. It is therefore proposed here that the work achieved so far by the RHpE can be of value for observers to recognize that these behaviors may indicate pain but as a diagnostic tool, the RHpE requires further development. Our evaluation of the RHpE is that it is impaired by some flaws in the definitions and that an interdisciplinary approach with substantial ethological input will greatly improve its accuracy and utility. In addition, there is a risk in applying an accumulative clinical threshold when all of the items within an ethogram are assigned equal weighting without an evidence-base for such weighting. Apart from pain and lameness, many other aspects of riding can contribute to suboptimal welfare in the ridden horse and result in the same behaviors highlighted in the RHpE. While recognizing that the RHpE may help to rule in or out problems on the differential diagnosis list and that it has not been proposed as a standalone technique, we see a risk in it being adopted without further development. Public acceptance of future use of horses for elite sports likely depends on whether the international and national riding federations can provide credible, objective evidence that horse welfare is truly paramount at all times.